1 // SPDX-License-Identifier: GPL-2.0 2 3 #include <linux/compiler_types.h> 4 #include <linux/errno.h> 5 #include <linux/fs.h> 6 #include <linux/fsnotify.h> 7 #include <linux/gfp.h> 8 #include <linux/idr.h> 9 #include <linux/init.h> 10 #include <linux/ipc_namespace.h> 11 #include <linux/kdev_t.h> 12 #include <linux/kernel.h> 13 #include <linux/list.h> 14 #include <linux/namei.h> 15 #include <linux/magic.h> 16 #include <linux/major.h> 17 #include <linux/miscdevice.h> 18 #include <linux/module.h> 19 #include <linux/mutex.h> 20 #include <linux/mount.h> 21 #include <linux/fs_parser.h> 22 #include <linux/sched.h> 23 #include <linux/seq_file.h> 24 #include <linux/slab.h> 25 #include <linux/spinlock_types.h> 26 #include <linux/stddef.h> 27 #include <linux/string.h> 28 #include <linux/types.h> 29 #include <linux/uaccess.h> 30 #include <linux/user_namespace.h> 31 #include <linux/xarray.h> 32 #include <uapi/linux/android/binder.h> 33 #include <uapi/linux/android/binderfs.h> 34 35 #include "binder_internal.h" 36 37 #define FIRST_INODE 1 38 #define SECOND_INODE 2 39 #define INODE_OFFSET 3 40 #define BINDERFS_MAX_MINOR (1U << MINORBITS) 41 /* Ensure that the initial ipc namespace always has devices available. */ 42 #define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4) 43 44 static dev_t binderfs_dev; 45 static DEFINE_MUTEX(binderfs_minors_mutex); 46 static DEFINE_IDA(binderfs_minors); 47 48 enum binderfs_param { 49 Opt_max, 50 Opt_stats_mode, 51 }; 52 53 enum binderfs_stats_mode { 54 binderfs_stats_mode_unset, 55 binderfs_stats_mode_global, 56 }; 57 58 struct binder_features { 59 bool oneway_spam_detection; 60 bool extended_error; 61 bool freeze_notification; 62 }; 63 64 static const struct constant_table binderfs_param_stats[] = { 65 { "global", binderfs_stats_mode_global }, 66 {} 67 }; 68 69 static const struct fs_parameter_spec binderfs_fs_parameters[] = { 70 fsparam_u32("max", Opt_max), 71 fsparam_enum("stats", Opt_stats_mode, binderfs_param_stats), 72 {} 73 }; 74 75 static struct binder_features binder_features = { 76 .oneway_spam_detection = true, 77 .extended_error = true, 78 .freeze_notification = true, 79 }; 80 81 static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb) 82 { 83 return sb->s_fs_info; 84 } 85 86 bool is_binderfs_device(const struct inode *inode) 87 { 88 if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC) 89 return true; 90 91 return false; 92 } 93 94 /** 95 * binderfs_binder_device_create - allocate inode from super block of a 96 * binderfs mount 97 * @ref_inode: inode from which the super block will be taken 98 * @userp: buffer to copy information about new device for userspace to 99 * @req: struct binderfs_device as copied from userspace 100 * 101 * This function allocates a new binder_device and reserves a new minor 102 * number for it. 103 * Minor numbers are limited and tracked globally in binderfs_minors. The 104 * function will stash a struct binder_device for the specific binder 105 * device in i_private of the inode. 106 * It will go on to allocate a new inode from the super block of the 107 * filesystem mount, stash a struct binder_device in its i_private field 108 * and attach a dentry to that inode. 109 * 110 * Return: 0 on success, negative errno on failure 111 */ 112 static int binderfs_binder_device_create(struct inode *ref_inode, 113 struct binderfs_device __user *userp, 114 struct binderfs_device *req) 115 { 116 int minor, ret; 117 struct dentry *dentry, *root; 118 struct binder_device *device; 119 char *name = NULL; 120 size_t name_len; 121 struct inode *inode = NULL; 122 struct super_block *sb = ref_inode->i_sb; 123 struct binderfs_info *info = sb->s_fs_info; 124 #if defined(CONFIG_IPC_NS) 125 bool use_reserve = (info->ipc_ns == &init_ipc_ns); 126 #else 127 bool use_reserve = true; 128 #endif 129 130 /* Reserve new minor number for the new device. */ 131 mutex_lock(&binderfs_minors_mutex); 132 if (++info->device_count <= info->mount_opts.max) 133 minor = ida_alloc_max(&binderfs_minors, 134 use_reserve ? BINDERFS_MAX_MINOR : 135 BINDERFS_MAX_MINOR_CAPPED, 136 GFP_KERNEL); 137 else 138 minor = -ENOSPC; 139 if (minor < 0) { 140 --info->device_count; 141 mutex_unlock(&binderfs_minors_mutex); 142 return minor; 143 } 144 mutex_unlock(&binderfs_minors_mutex); 145 146 ret = -ENOMEM; 147 device = kzalloc(sizeof(*device), GFP_KERNEL); 148 if (!device) 149 goto err; 150 151 inode = new_inode(sb); 152 if (!inode) 153 goto err; 154 155 inode->i_ino = minor + INODE_OFFSET; 156 simple_inode_init_ts(inode); 157 init_special_inode(inode, S_IFCHR | 0600, 158 MKDEV(MAJOR(binderfs_dev), minor)); 159 inode->i_fop = &binder_fops; 160 inode->i_uid = info->root_uid; 161 inode->i_gid = info->root_gid; 162 163 req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */ 164 name_len = strlen(req->name); 165 /* Make sure to include terminating NUL byte */ 166 name = kmemdup(req->name, name_len + 1, GFP_KERNEL); 167 if (!name) 168 goto err; 169 170 refcount_set(&device->ref, 1); 171 device->binderfs_inode = inode; 172 device->context.binder_context_mgr_uid = INVALID_UID; 173 device->context.name = name; 174 device->miscdev.name = name; 175 device->miscdev.minor = minor; 176 mutex_init(&device->context.context_mgr_node_lock); 177 178 req->major = MAJOR(binderfs_dev); 179 req->minor = minor; 180 181 if (userp && copy_to_user(userp, req, sizeof(*req))) { 182 ret = -EFAULT; 183 goto err; 184 } 185 186 root = sb->s_root; 187 inode_lock(d_inode(root)); 188 189 /* look it up */ 190 dentry = lookup_one_len(name, root, name_len); 191 if (IS_ERR(dentry)) { 192 inode_unlock(d_inode(root)); 193 ret = PTR_ERR(dentry); 194 goto err; 195 } 196 197 if (d_really_is_positive(dentry)) { 198 /* already exists */ 199 dput(dentry); 200 inode_unlock(d_inode(root)); 201 ret = -EEXIST; 202 goto err; 203 } 204 205 inode->i_private = device; 206 d_instantiate(dentry, inode); 207 fsnotify_create(root->d_inode, dentry); 208 inode_unlock(d_inode(root)); 209 210 return 0; 211 212 err: 213 kfree(name); 214 kfree(device); 215 mutex_lock(&binderfs_minors_mutex); 216 --info->device_count; 217 ida_free(&binderfs_minors, minor); 218 mutex_unlock(&binderfs_minors_mutex); 219 iput(inode); 220 221 return ret; 222 } 223 224 /** 225 * binder_ctl_ioctl - handle binder device node allocation requests 226 * 227 * The request handler for the binder-control device. All requests operate on 228 * the binderfs mount the binder-control device resides in: 229 * - BINDER_CTL_ADD 230 * Allocate a new binder device. 231 * 232 * Return: %0 on success, negative errno on failure. 233 */ 234 static long binder_ctl_ioctl(struct file *file, unsigned int cmd, 235 unsigned long arg) 236 { 237 int ret = -EINVAL; 238 struct inode *inode = file_inode(file); 239 struct binderfs_device __user *device = (struct binderfs_device __user *)arg; 240 struct binderfs_device device_req; 241 242 switch (cmd) { 243 case BINDER_CTL_ADD: 244 ret = copy_from_user(&device_req, device, sizeof(device_req)); 245 if (ret) { 246 ret = -EFAULT; 247 break; 248 } 249 250 ret = binderfs_binder_device_create(inode, device, &device_req); 251 break; 252 default: 253 break; 254 } 255 256 return ret; 257 } 258 259 static void binderfs_evict_inode(struct inode *inode) 260 { 261 struct binder_device *device = inode->i_private; 262 struct binderfs_info *info = BINDERFS_SB(inode->i_sb); 263 264 clear_inode(inode); 265 266 if (!S_ISCHR(inode->i_mode) || !device) 267 return; 268 269 mutex_lock(&binderfs_minors_mutex); 270 --info->device_count; 271 ida_free(&binderfs_minors, device->miscdev.minor); 272 mutex_unlock(&binderfs_minors_mutex); 273 274 if (refcount_dec_and_test(&device->ref)) { 275 kfree(device->context.name); 276 kfree(device); 277 } 278 } 279 280 static int binderfs_fs_context_parse_param(struct fs_context *fc, 281 struct fs_parameter *param) 282 { 283 int opt; 284 struct binderfs_mount_opts *ctx = fc->fs_private; 285 struct fs_parse_result result; 286 287 opt = fs_parse(fc, binderfs_fs_parameters, param, &result); 288 if (opt < 0) 289 return opt; 290 291 switch (opt) { 292 case Opt_max: 293 if (result.uint_32 > BINDERFS_MAX_MINOR) 294 return invalfc(fc, "Bad value for '%s'", param->key); 295 296 ctx->max = result.uint_32; 297 break; 298 case Opt_stats_mode: 299 if (!capable(CAP_SYS_ADMIN)) 300 return -EPERM; 301 302 ctx->stats_mode = result.uint_32; 303 break; 304 default: 305 return invalfc(fc, "Unsupported parameter '%s'", param->key); 306 } 307 308 return 0; 309 } 310 311 static int binderfs_fs_context_reconfigure(struct fs_context *fc) 312 { 313 struct binderfs_mount_opts *ctx = fc->fs_private; 314 struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb); 315 316 if (info->mount_opts.stats_mode != ctx->stats_mode) 317 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount"); 318 319 info->mount_opts.stats_mode = ctx->stats_mode; 320 info->mount_opts.max = ctx->max; 321 return 0; 322 } 323 324 static int binderfs_show_options(struct seq_file *seq, struct dentry *root) 325 { 326 struct binderfs_info *info = BINDERFS_SB(root->d_sb); 327 328 if (info->mount_opts.max <= BINDERFS_MAX_MINOR) 329 seq_printf(seq, ",max=%d", info->mount_opts.max); 330 331 switch (info->mount_opts.stats_mode) { 332 case binderfs_stats_mode_unset: 333 break; 334 case binderfs_stats_mode_global: 335 seq_printf(seq, ",stats=global"); 336 break; 337 } 338 339 return 0; 340 } 341 342 static const struct super_operations binderfs_super_ops = { 343 .evict_inode = binderfs_evict_inode, 344 .show_options = binderfs_show_options, 345 .statfs = simple_statfs, 346 }; 347 348 static inline bool is_binderfs_control_device(const struct dentry *dentry) 349 { 350 struct binderfs_info *info = dentry->d_sb->s_fs_info; 351 352 return info->control_dentry == dentry; 353 } 354 355 static int binderfs_rename(struct mnt_idmap *idmap, 356 struct inode *old_dir, struct dentry *old_dentry, 357 struct inode *new_dir, struct dentry *new_dentry, 358 unsigned int flags) 359 { 360 if (is_binderfs_control_device(old_dentry) || 361 is_binderfs_control_device(new_dentry)) 362 return -EPERM; 363 364 return simple_rename(idmap, old_dir, old_dentry, new_dir, 365 new_dentry, flags); 366 } 367 368 static int binderfs_unlink(struct inode *dir, struct dentry *dentry) 369 { 370 if (is_binderfs_control_device(dentry)) 371 return -EPERM; 372 373 return simple_unlink(dir, dentry); 374 } 375 376 static const struct file_operations binder_ctl_fops = { 377 .owner = THIS_MODULE, 378 .open = nonseekable_open, 379 .unlocked_ioctl = binder_ctl_ioctl, 380 .compat_ioctl = binder_ctl_ioctl, 381 .llseek = noop_llseek, 382 }; 383 384 /** 385 * binderfs_binder_ctl_create - create a new binder-control device 386 * @sb: super block of the binderfs mount 387 * 388 * This function creates a new binder-control device node in the binderfs mount 389 * referred to by @sb. 390 * 391 * Return: 0 on success, negative errno on failure 392 */ 393 static int binderfs_binder_ctl_create(struct super_block *sb) 394 { 395 int minor, ret; 396 struct dentry *dentry; 397 struct binder_device *device; 398 struct inode *inode = NULL; 399 struct dentry *root = sb->s_root; 400 struct binderfs_info *info = sb->s_fs_info; 401 #if defined(CONFIG_IPC_NS) 402 bool use_reserve = (info->ipc_ns == &init_ipc_ns); 403 #else 404 bool use_reserve = true; 405 #endif 406 407 device = kzalloc(sizeof(*device), GFP_KERNEL); 408 if (!device) 409 return -ENOMEM; 410 411 /* If we have already created a binder-control node, return. */ 412 if (info->control_dentry) { 413 ret = 0; 414 goto out; 415 } 416 417 ret = -ENOMEM; 418 inode = new_inode(sb); 419 if (!inode) 420 goto out; 421 422 /* Reserve a new minor number for the new device. */ 423 mutex_lock(&binderfs_minors_mutex); 424 minor = ida_alloc_max(&binderfs_minors, 425 use_reserve ? BINDERFS_MAX_MINOR : 426 BINDERFS_MAX_MINOR_CAPPED, 427 GFP_KERNEL); 428 mutex_unlock(&binderfs_minors_mutex); 429 if (minor < 0) { 430 ret = minor; 431 goto out; 432 } 433 434 inode->i_ino = SECOND_INODE; 435 simple_inode_init_ts(inode); 436 init_special_inode(inode, S_IFCHR | 0600, 437 MKDEV(MAJOR(binderfs_dev), minor)); 438 inode->i_fop = &binder_ctl_fops; 439 inode->i_uid = info->root_uid; 440 inode->i_gid = info->root_gid; 441 442 refcount_set(&device->ref, 1); 443 device->binderfs_inode = inode; 444 device->miscdev.minor = minor; 445 446 dentry = d_alloc_name(root, "binder-control"); 447 if (!dentry) 448 goto out; 449 450 inode->i_private = device; 451 info->control_dentry = dentry; 452 d_add(dentry, inode); 453 454 return 0; 455 456 out: 457 kfree(device); 458 iput(inode); 459 460 return ret; 461 } 462 463 static const struct inode_operations binderfs_dir_inode_operations = { 464 .lookup = simple_lookup, 465 .rename = binderfs_rename, 466 .unlink = binderfs_unlink, 467 }; 468 469 static struct inode *binderfs_make_inode(struct super_block *sb, int mode) 470 { 471 struct inode *ret; 472 473 ret = new_inode(sb); 474 if (ret) { 475 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET); 476 ret->i_mode = mode; 477 simple_inode_init_ts(ret); 478 } 479 return ret; 480 } 481 482 static struct dentry *binderfs_create_dentry(struct dentry *parent, 483 const char *name) 484 { 485 struct dentry *dentry; 486 487 dentry = lookup_one_len(name, parent, strlen(name)); 488 if (IS_ERR(dentry)) 489 return dentry; 490 491 /* Return error if the file/dir already exists. */ 492 if (d_really_is_positive(dentry)) { 493 dput(dentry); 494 return ERR_PTR(-EEXIST); 495 } 496 497 return dentry; 498 } 499 500 void binderfs_remove_file(struct dentry *dentry) 501 { 502 struct inode *parent_inode; 503 504 parent_inode = d_inode(dentry->d_parent); 505 inode_lock(parent_inode); 506 if (simple_positive(dentry)) { 507 dget(dentry); 508 simple_unlink(parent_inode, dentry); 509 d_delete(dentry); 510 dput(dentry); 511 } 512 inode_unlock(parent_inode); 513 } 514 515 struct dentry *binderfs_create_file(struct dentry *parent, const char *name, 516 const struct file_operations *fops, 517 void *data) 518 { 519 struct dentry *dentry; 520 struct inode *new_inode, *parent_inode; 521 struct super_block *sb; 522 523 parent_inode = d_inode(parent); 524 inode_lock(parent_inode); 525 526 dentry = binderfs_create_dentry(parent, name); 527 if (IS_ERR(dentry)) 528 goto out; 529 530 sb = parent_inode->i_sb; 531 new_inode = binderfs_make_inode(sb, S_IFREG | 0444); 532 if (!new_inode) { 533 dput(dentry); 534 dentry = ERR_PTR(-ENOMEM); 535 goto out; 536 } 537 538 new_inode->i_fop = fops; 539 new_inode->i_private = data; 540 d_instantiate(dentry, new_inode); 541 fsnotify_create(parent_inode, dentry); 542 543 out: 544 inode_unlock(parent_inode); 545 return dentry; 546 } 547 548 static struct dentry *binderfs_create_dir(struct dentry *parent, 549 const char *name) 550 { 551 struct dentry *dentry; 552 struct inode *new_inode, *parent_inode; 553 struct super_block *sb; 554 555 parent_inode = d_inode(parent); 556 inode_lock(parent_inode); 557 558 dentry = binderfs_create_dentry(parent, name); 559 if (IS_ERR(dentry)) 560 goto out; 561 562 sb = parent_inode->i_sb; 563 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755); 564 if (!new_inode) { 565 dput(dentry); 566 dentry = ERR_PTR(-ENOMEM); 567 goto out; 568 } 569 570 new_inode->i_fop = &simple_dir_operations; 571 new_inode->i_op = &simple_dir_inode_operations; 572 573 set_nlink(new_inode, 2); 574 d_instantiate(dentry, new_inode); 575 inc_nlink(parent_inode); 576 fsnotify_mkdir(parent_inode, dentry); 577 578 out: 579 inode_unlock(parent_inode); 580 return dentry; 581 } 582 583 static int binder_features_show(struct seq_file *m, void *unused) 584 { 585 bool *feature = m->private; 586 587 seq_printf(m, "%d\n", *feature); 588 589 return 0; 590 } 591 DEFINE_SHOW_ATTRIBUTE(binder_features); 592 593 static int init_binder_features(struct super_block *sb) 594 { 595 struct dentry *dentry, *dir; 596 597 dir = binderfs_create_dir(sb->s_root, "features"); 598 if (IS_ERR(dir)) 599 return PTR_ERR(dir); 600 601 dentry = binderfs_create_file(dir, "oneway_spam_detection", 602 &binder_features_fops, 603 &binder_features.oneway_spam_detection); 604 if (IS_ERR(dentry)) 605 return PTR_ERR(dentry); 606 607 dentry = binderfs_create_file(dir, "extended_error", 608 &binder_features_fops, 609 &binder_features.extended_error); 610 if (IS_ERR(dentry)) 611 return PTR_ERR(dentry); 612 613 dentry = binderfs_create_file(dir, "freeze_notification", 614 &binder_features_fops, 615 &binder_features.freeze_notification); 616 if (IS_ERR(dentry)) 617 return PTR_ERR(dentry); 618 619 return 0; 620 } 621 622 static int init_binder_logs(struct super_block *sb) 623 { 624 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir; 625 const struct binder_debugfs_entry *db_entry; 626 struct binderfs_info *info; 627 int ret = 0; 628 629 binder_logs_root_dir = binderfs_create_dir(sb->s_root, 630 "binder_logs"); 631 if (IS_ERR(binder_logs_root_dir)) { 632 ret = PTR_ERR(binder_logs_root_dir); 633 goto out; 634 } 635 636 binder_for_each_debugfs_entry(db_entry) { 637 dentry = binderfs_create_file(binder_logs_root_dir, 638 db_entry->name, 639 db_entry->fops, 640 db_entry->data); 641 if (IS_ERR(dentry)) { 642 ret = PTR_ERR(dentry); 643 goto out; 644 } 645 } 646 647 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc"); 648 if (IS_ERR(proc_log_dir)) { 649 ret = PTR_ERR(proc_log_dir); 650 goto out; 651 } 652 info = sb->s_fs_info; 653 info->proc_log_dir = proc_log_dir; 654 655 out: 656 return ret; 657 } 658 659 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc) 660 { 661 int ret; 662 struct binderfs_info *info; 663 struct binderfs_mount_opts *ctx = fc->fs_private; 664 struct inode *inode = NULL; 665 struct binderfs_device device_info = {}; 666 const char *name; 667 size_t len; 668 669 sb->s_blocksize = PAGE_SIZE; 670 sb->s_blocksize_bits = PAGE_SHIFT; 671 672 /* 673 * The binderfs filesystem can be mounted by userns root in a 674 * non-initial userns. By default such mounts have the SB_I_NODEV flag 675 * set in s_iflags to prevent security issues where userns root can 676 * just create random device nodes via mknod() since it owns the 677 * filesystem mount. But binderfs does not allow to create any files 678 * including devices nodes. The only way to create binder devices nodes 679 * is through the binder-control device which userns root is explicitly 680 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both 681 * necessary and safe. 682 */ 683 sb->s_iflags &= ~SB_I_NODEV; 684 sb->s_iflags |= SB_I_NOEXEC; 685 sb->s_magic = BINDERFS_SUPER_MAGIC; 686 sb->s_op = &binderfs_super_ops; 687 sb->s_time_gran = 1; 688 689 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL); 690 if (!sb->s_fs_info) 691 return -ENOMEM; 692 info = sb->s_fs_info; 693 694 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns); 695 696 info->root_gid = make_kgid(sb->s_user_ns, 0); 697 if (!gid_valid(info->root_gid)) 698 info->root_gid = GLOBAL_ROOT_GID; 699 info->root_uid = make_kuid(sb->s_user_ns, 0); 700 if (!uid_valid(info->root_uid)) 701 info->root_uid = GLOBAL_ROOT_UID; 702 info->mount_opts.max = ctx->max; 703 info->mount_opts.stats_mode = ctx->stats_mode; 704 705 inode = new_inode(sb); 706 if (!inode) 707 return -ENOMEM; 708 709 inode->i_ino = FIRST_INODE; 710 inode->i_fop = &simple_dir_operations; 711 inode->i_mode = S_IFDIR | 0755; 712 simple_inode_init_ts(inode); 713 inode->i_op = &binderfs_dir_inode_operations; 714 set_nlink(inode, 2); 715 716 sb->s_root = d_make_root(inode); 717 if (!sb->s_root) 718 return -ENOMEM; 719 720 ret = binderfs_binder_ctl_create(sb); 721 if (ret) 722 return ret; 723 724 name = binder_devices_param; 725 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 726 strscpy(device_info.name, name, len + 1); 727 ret = binderfs_binder_device_create(inode, NULL, &device_info); 728 if (ret) 729 return ret; 730 name += len; 731 if (*name == ',') 732 name++; 733 } 734 735 ret = init_binder_features(sb); 736 if (ret) 737 return ret; 738 739 if (info->mount_opts.stats_mode == binderfs_stats_mode_global) 740 return init_binder_logs(sb); 741 742 return 0; 743 } 744 745 static int binderfs_fs_context_get_tree(struct fs_context *fc) 746 { 747 return get_tree_nodev(fc, binderfs_fill_super); 748 } 749 750 static void binderfs_fs_context_free(struct fs_context *fc) 751 { 752 struct binderfs_mount_opts *ctx = fc->fs_private; 753 754 kfree(ctx); 755 } 756 757 static const struct fs_context_operations binderfs_fs_context_ops = { 758 .free = binderfs_fs_context_free, 759 .get_tree = binderfs_fs_context_get_tree, 760 .parse_param = binderfs_fs_context_parse_param, 761 .reconfigure = binderfs_fs_context_reconfigure, 762 }; 763 764 static int binderfs_init_fs_context(struct fs_context *fc) 765 { 766 struct binderfs_mount_opts *ctx; 767 768 ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL); 769 if (!ctx) 770 return -ENOMEM; 771 772 ctx->max = BINDERFS_MAX_MINOR; 773 ctx->stats_mode = binderfs_stats_mode_unset; 774 775 fc->fs_private = ctx; 776 fc->ops = &binderfs_fs_context_ops; 777 778 return 0; 779 } 780 781 static void binderfs_kill_super(struct super_block *sb) 782 { 783 struct binderfs_info *info = sb->s_fs_info; 784 785 /* 786 * During inode eviction struct binderfs_info is needed. 787 * So first wipe the super_block then free struct binderfs_info. 788 */ 789 kill_litter_super(sb); 790 791 if (info && info->ipc_ns) 792 put_ipc_ns(info->ipc_ns); 793 794 kfree(info); 795 } 796 797 static struct file_system_type binder_fs_type = { 798 .name = "binder", 799 .init_fs_context = binderfs_init_fs_context, 800 .parameters = binderfs_fs_parameters, 801 .kill_sb = binderfs_kill_super, 802 .fs_flags = FS_USERNS_MOUNT, 803 }; 804 805 int __init init_binderfs(void) 806 { 807 int ret; 808 const char *name; 809 size_t len; 810 811 /* Verify that the default binderfs device names are valid. */ 812 name = binder_devices_param; 813 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 814 if (len > BINDERFS_MAX_NAME) 815 return -E2BIG; 816 name += len; 817 if (*name == ',') 818 name++; 819 } 820 821 /* Allocate new major number for binderfs. */ 822 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR, 823 "binder"); 824 if (ret) 825 return ret; 826 827 ret = register_filesystem(&binder_fs_type); 828 if (ret) { 829 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR); 830 return ret; 831 } 832 833 return ret; 834 } 835